Add GetDBTableGuid method

GameObjectMethods.h

@@ -146,6 +146,22 @@ namespace LuaGameObject
         return 1;
     }
 
+    /**
+     * Returns the guid of the [GameObject] that is used as the ID in the database
+     *
+     * @return uint32 dbguid
+     */
+    int GetDBTableGUIDLow(Eluna* /*E*/, lua_State* L, GameObject* go)
+    {
+#ifdef TRINITY
+        Eluna::Push(L, go->GetDBTableGUIDLow());
+#else
+        // on mangos based this is same as lowguid
+        Eluna::Push(L, go->GetGUIDLow());
+#endif
+        return 1;
+    }
+
     /**
      * Sets the state of a [GameObject]
      *